Animal BehaviourArea of Study: Adaptations of Animals

Animal behaviour – key knowledge

Adaptations of animals include behaviours, characteristics that increase individual’s chance of survival and reproduction.

Animals forage or hunt for food, fight for resources, defend territories, raise offspring and live in social groups.

Some behaviours are innate (instinctive) and others are learned.

What is behaviour?Behaviour refers to the coordinated activities of an animal that are reproduced in response to internal or external stimuli.

Individual behaviour = Includes those related to movement or physiological regulation (eg. dogs panting when hot).

Social behaviour = Related to interactions with other organisms (eg. bees in a hive). Social behaviours are related to courtship, reproduction and parenting; feeding and defence strategies; and communication within and between groups of animals.

What is behaviour?Behaviour refers to the coordinated activities of an animal that are reproduced in response to internal or external stimuli.

Individual

Social

Behaviour depends on detecting a stimulus

Behaviour depends on the detection of internal or external stimuli by sensory organs and the transmission of this information through the nervous system.

Behaviour depends on detecting a stimulus

As a result of natural selection, patterns of behaviour that increase the survival and successful reproduction of individuals have evolved.

Behaviour depends on detecting a stimulus

Spitfires live in groups throughout the day, emerging from their bundle of bodies to feed on young leaves under the cover of darkness.

Behaviour depends on detecting a stimulus

What environmental stimulus causes them to huddle together?

Behaviour depends on detecting a stimulus

How could natural selection have led to the evolution of this behaviour?

Inborn or learned behaviour

Some behaviours are innate (inborn) and some are learned.

It is an oversimplification to divide behaviour into two discrete categories – innate (genetic) and learned (environmental).

Inborn or learned behaviour

Even the most rigid and automatic behaviours are affected by environmental conditions, and learning has a distinct genetic component.

Observable behaviour ranges between highly instinctive patters (such as web-building) and highly learned (such as house building by humans).

Question

Youtube video of a spider spinning a web

Spiders know how to spin webs instinctively. Can they learn how to make a better one as well? What advantage does this innate ability to build a web have on a spider’s chance of survival and reproductive success?

Innate behaviour

Innate behaviour eliminates the time-consuming process of learning, and may allow rapid response.

Generally any behaviour that is not learned.

Advantage – it can be produced the first time – no practice needed.

Innate behaviour

Produced by a particular inherited pattern of organisation of nerve cells in the nervous system, occurring automatically in response to a specific stimulus.

Instinct is the innate ability to complete a specific behaviour pattern; no conscious intention is involved.

Question

Youtube video about flirting

What do you think? Is flirting innate or learnt?

Why does it not begin in most people until their teenage years?

Releasers are signal signs

Innate behaviour occurs in response to specific signals, called sign stimuli or releasers.

The degree of responsiveness of an animal to a releaser may vary according to particular environmental conditions, such as the time of day or season of the year.

Releasers are signal signs

Innate behaviour occurs in response to specific signals, called sign stimuli or releasers.

Male sparrows show territorial behaviour (and sing incessantly) in spring when their testosterone levels are high.

The increase hormone level is the results of nights becoming shorter as spring approaches.

Releasers are signal signs

Releasers may also involve other senses;

sound (hens respond to the sound of their chicks distress calls, not the sight of chicks in trouble)

chemical (pheromones that stimulate mating in insects)

Question

Youtube video about migration

At a certain time in the year Frigate birds, Boobies and Green Turtles travel thousands of kilometers to their breeding grounds on Ascension Island. Describe how releasers might affect the expression of this innate behaviour.

Question

Find another example of migration in animals and identify the releaser.

Releasers initiate behaviour automatically

From birth, herring gull chicks peck at a red spot on their parent’s bill in order to get food. They will also readily peck at red dots on the end of a wagging pencil, and a wagging model with the red spot on its head. Herring gull chicks respond poorly to stationary models and models with no spot.

Releasers initiate behaviour automatically

Silhouettes of predatory birds trigger escape responses in their prey. This can be unlearnt.

Releasers initiate behaviour automatically

Fixed action patterns are innate behavioural responses that are particularly strong and once triggered, proceed to completion regardless of any other input.

Nipple finding behaviour in babies,

feeding of young in birds and

egg-rolling by geese.

Releasers initiate behaviour automatically

Fixed action patterns are innate behavioural responses that are particularly strong and once triggered, proceed to completion regardless of any other input.

Nipple finding behaviour in babies,

feeding of young in birds and

egg-rolling by geese.

Releasers initiate behaviour automatically

Fixed action patterns are innate behavioural responses that are particularly strong and once triggered, proceed to completion regardless of any other input.

Nipple finding behaviour in babies,

feeding of young in birds and

egg-rolling by geese.

Releasers initiate behaviour automatically

Fixed action patterns are innate behavioural responses that are particularly strong and once triggered, proceed to completion regardless of any other input. Stimulus Behaviour

patternEvolutionary significance

Nipple finding behaviour in babies

feeding of young in birds

egg-rolling by geese

Learning

Many behaviours have a significant component that is learned.It allows the

modification of a behavioural response to a particular stimulus on the basis of previous experience.

Wikipedia ref

Learning

Many behaviours have a significant component that is learned.Learning depends on

memory – the ability to store and retrieve information about past events.

Wikipedia ref

Learning

Learning provides flexibility, allowing an animal to change its behaviour in response to unpredictable changes.

Contrast the following in terms of the advantages they provide to a individual’s or species’ survival and reproductive success using the information in these notes…1. Innate behaviour in animals2. Learnt behaviour in animals

Question

What types of animals learn?

All animalsLearning and intelligence:

Among vertebrates, the ability to learn is sometimes taken as an indication of intelligence.

Octopuses, in particular, have highly developed sensory organs, particularly their eyes, which have the same structure and operate in a similar way to vertebrate eyes.

What types of animals learn?

Learning depends onThe ability to detect change

The ability to understand that change

The ability to change the way the organism behaves… and sometimes…

The ability of a species to communicate to one another.

Learning examples

Youtube video of an octopus hatching and later learning how to open a jar to get a meal.

Youtube video of crows learning how to open particularly tricky nuts

Question

Youtube video of communal nest building birds

Is the social nest building of these birds innate or learnt behaviour or a mixture of both?

Types of learning

Imprinting - Imprinting is the term used in psychology and ethology to describe any learning which occurs at a particular age or a particular life stage that is rapid and apparently independent of the consequences of behavior. (ref)

Habituation - the gradual fading of a response (usually an innate response) to a stimulus that proves to be safe or irrelevant.

Associative learning (conditioning) -

Trial and error learning –

Observational -

Insight -

Imprinting

In some animals, the capacity for learning about a particular stimulus is very high at certain stages of development. The period in which imprinting can

occur is quite short and usually occurs early in life.

 learning that occurs during imprinting is rapid and cannot be reversed.

Imprinting

For example, ducklings begin walking within hours of hatching and ‘imprint’ on their mother; that is, they follow her wherever she goes.

Question

Identify: How could imprinting benefit the reproductive success of individuals and / or the survival of the species?

Question

Youtube video about Konrad Lorenz and imprinting

Discuss: Adopted children often feel a real urge to find their real parents once they grow up and experience an enormous relief when they do. Do you think that imprinting is different in humans to animals? Discuss.

Habituation

A scarecrow might initially frighten birds away from a fruit crop, but before long the birds are likely to be seen perched on the scarecrow’s shoulders. Fish in a tank will quickly learn to ignore repeated tapping on their tank and overhead shadows caused by a waving hand. These behaviours are examples of habituation, which is the simplest and most common form of learning.

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Habituation

The ability to get used to a repeated stimulus, such as noise, is called habituation.

Habituation

Habituation involves gradual fading of a response (usually an innate response) to a stimulus that proves to be safe or irrelevant.

Habituation

The stimulus is initially unfamiliar and the response is defensive, such as startle or escape response.

Habituation

After repeated stimulation, the magnitude of the response becomes less and less.

The advantage of habituation is that an individual does not waste time and energy reacting defensively where there is no danger.

Question

Youtube video showing how a rat learns not to be startled by a loud noise.

Discuss: what examples of habituation in humans do you know of?

Associative learning

Example: pets, Pavlov’s dogs.Associative learning (also known as classical

conditioning) involves the association of a new signal with the innate signal that triggers a particular behavioural response.

Just as associative learning can be induced, so it can be lost again if the association between the two signal disappears. This loss of learning is called extinction.

Question

Youtube video explaining Pavlov’s original experiments.

Youtube video explaining how Pavlov’s experiments with dogs can help us understand human reactions to mobile phone ringing.

Discuss: what you do when a mobile phone rings. Do you do this for every type of ring?

Trial-and-error learning

In this form of learning an animal carries out a particular behaviour and, remembering the attempt and its outcomes, modifies its subsequent behaviour in order to improve the chances of success.The animal learns from its mistakes.

Trial-and-error learning involves refining behaviour to suit a particular set of environmental conditions.

Observational learningMany higher vertebrates, particularly

birds and animals, can learn particular patterns of behaviour by observing other animals.Most likely gained from parents and

peers.It is the means by which cultural

information is transferred from individual to individual, and from generation to generation.

Insight learning the most complex kind of learning.

requires complex brains like those found in some mammals, such as dolphins and the great apes (including humans).

A problem is solved as the result of thinking about it rather than by trial and error.

It is related to the ability of an animal to apply past experience to solving a new problem without a trial-and-error period.

Involves the use of reason.

Play forms an important part in developing problem-solving skills for later use.

Behaviour for maintenance

The basic behaviour patterns of individual animals enable them to meet their requirements for surviving and maintaining their well being.Maintenance behaviours occupy much of an animal’s

time. Includes activities such as feeding, drinking,

ventilation, finding or making shelter, regulating temperature, and grooming.

To catch food and avoid being eaten, animal consumers show certain behavioural patterns (adaptations) that are of benefit to their survival.

Behaviour for maintenance

Patterns of behaviour are generally adaptive; that is they are of benefit to the individual organism.Animals must divide their time between these

different activities.

Often it is necessary to change from one behaviour to another when circumstances change (eg. from eating to fleeing if a predator approaches).

A particular behaviour will also depend on the physiological state of the animal (eg. a hungry jumping spider is more likely to show predatory behaviour than a well-fed one).

Rhythmic activities

Periods of activity and inactivity alternate in most animals, often on a daily basis.Daily cycles are known as circadian

rhythms.Lunar cycles are cycles that coincide

with the waxing and waning of the moon.

Tidal rhythms affect many organisms.

Rhythmic activities

Circannual rhythms are yearly rhythms, eg. migrations of some birds and whales, the hibernations of animals during winter.

Circadian rhythms are biological clocks. They are internal timers that operate in the absence on any external cues. In vertebrates, ‘clocks’ are usually synchronised by the

day/night cycle of light intensity. At night, in the absence of bright light, the hormone melatonin is produced by the pineal gland. Blood levels of this hormone fall when light enters the eyes. The level of melatonin in the blood therefore reflects the time of day. The cycle of its increasing and decreasing level indicates the length of the night and thus the season.

Movement

Animals move to obtain food, seek shelter, interact with other animals and seek out mates. Aquatic animals move about using cilia,

flagella, tentacles, fins or flippers.

Bivalve molluscs clap their shells together and octopuses and squids use jet propulsion for rapid escape.

Terrestrial animals crawl, walk, run, tunnel through the ground, or fly or glide through the air.

Feeding behaviour

Herbivores and predators know what to eat, where to find food, how to get it, and how to eat it.Feeding behaviour is an example

of a rhythmic behaviour.

Feeding behaviourFeeding may be: 

On an individual basis (eg. spider)On a group basis, in which members of a species

cooperate in some way to improve their chances of obtaining food (eg. humpback whales using bubble net feeding, common dolphins).

Feeding behaviour

Adaptations for feeding include physical characteristics, such as a carnivore’s sharp teeth for killing and tearing meat, but also behaviours for getting food.Many animals, particularly carnivores, spend a

lot of time resting, which conserves energy in between hunting trips.

Herbivores, such as koalas, often spend a large part of their day eating and chewing because plant fibre require considerable chewing and long periods in the gut for complete digestion.

Defensive behaviour

Searching for food runs the risk of exposure to predation during feeding.

Some animals ward off potential predators. For example: The venomous blue-ringed octopus quickly develops

characteristic brilliant blue rings on its tentacles as a warning sign when disturbed.

When alarmed the rattlesnake makes a rattling noise with the end of its tail.

Caterpillars have various defence mechanisms; some are well camouflaged and hide during the day; others taste bad and are covered with long defensive hairs.

Homeostatic behaviour

Maintenance behaviours include those that contribute to the homeostatic control of the internal environment, including water balance and temperature.

In many land vertebrates, fluctuations in internal body temperature are reduced by various behaviours. For example the behaviours of desert lizards include: Panting

Changing body posture and orientation

Moving into and out of shelter

Nocturnal activity.

Grooming and preening

Many animals clean the outer surface of their bodies. Grooming of fur by cats, tigers and

lions.

Grooming and preening

Preening of feathers is essential for the survival of birds.It involves spreading oil from a

gland at the base of the tail over the feathers that may have become ruffled, reuniting the hooks and hooklets of feathers.

This maintains their aerodynamic properties.

Home-building

Some animals do not make or find homes, but some construct elaborate structures. For example: Termite nests

Ant nests

Beehives

Spider webs

Rabbit burrows

Bird nests

In the case of a spider weaving its web, selection of building materials and construction of the web do not involve learned behaviour, but learning is fundamental to the construction of homes by humans.

Territorial behaviour

Many animals are territorial, meaning that they defend a certain area (territory) that contains a limited resource against occupation by other animals.

The boundaries of territories are patrolled, marked by scent and, in birds, indicated by singing.

Territories are often defended aggressively.

Territorial behaviour

The area over which an animal forages for food is its home range.

Sometimes an animal’s territory and home range are the same, but more often an animal will defend only a part of its home range, usually around its den or nest.

The advantage of this kind of behaviour to the individual is that a resource in a successfully defended territory does not have to be shared, and direct competition between individuals is reduced. However the animal must also expend energy and time defending its area.

Communication and social behaviour

Communication is the transfer of information from one animal to another.

The message or signal, which can be chemical, auditory, tactile, or visual, is passed between a sender and a receiver.

Communication usually occurs between members of the same species and is often associated with reproductive behaviour and with other social interactions within a group.

Communication between species occurs less frequently. It may be aggressive, defensive or cooperative.

The important components of communication include:Stimulus for the communication

Sender of a signal

Receiver to whom the signal is directed

The kind of signal sent

How the signal is sent

The behaviour of the receiver

The setting in which the communication occurs.

Communication and social behaviour

The making of a bower by a male bowerbird is a behavioural response to a particular stimulus. His behaviour sends a signal to female bowerbirds.

 

Aspect of communication Particular case with bowerbird

Stimulus Desire to mate

Sender Male bowerbird

Receiver to whom the signal is directed

Female ready to mate

Kind of signal Appearance of carefully made and decorated bower

How the signal is sent Visual image

Behaviour of receiver Attracted to the bower

Setting in which the communication occurs

Courtship behaviour

Some animals gain an advantage by mimicking the appearance and behaviour of another species.

Many species use striking colouration or calling signal to communicate with a potential mate.

Communication and social behaviour

Chemical communication by pheromones

Probably the most primitive and universally used form of communication.

Chemical communication is the release of chemicals into the environment that transmit information to those animals that have the appropriate receptors for receiving the chemical signal.

Chemical that carry messages between individuals of the same species are known as pheromones.

Visual signals

Visual communication is instantaneous and can carry a large amount of information.

Highly directional and the sender can be immediately identified.

The message may be continuous, eg. birds where the plumage of males and females is strikingly different.

Very few species rely solely on visual signals for communication.

Sounds as signals

Auditory communication can be used in the dark, and ‘around corners’.

It is faster than chemical communication and can carry lengthy and complex messages.

Sounds can carry a great deal of information if the pattern, frequency and pitch are varied.

Auditory communication requires complex sound-emitting and receiving organs, and is therefore found in animals with well-developed nervous systems.

Sounds as signals

Used by most vertebrates, many insects and some marine arthropods.

For example, sperm whales live in families of 10-12 individuals, including mothers, daughter, aunts and young males. They communicate in a language of clicks and pauses.

The most complex example of auditory communication is human speech.

Communication by touch

Tactile communication (communication by touch) is found more frequently in highly social groups of animals, such as ants, some birds and mammals.

It can only occur between individuals in close proximity.

The message is simple and does not require specialised sensory organs.

Social behaviour

Communication is most important in the lives of animals that form cooperative groups, known as societies.

Social behaviour involves interactions between members of a group.

Social behaviour can improve the defence of limited resources, foraging ability, surveillance and defence against predators and care of offspring.

Social behaviour

An important aspect of the social cohesiveness of the group is efficient two-way communication between its members.

Social interactions may involve cooperation as in mating or ensuring a food source.

Competition between individuals of the same species for resources often results in contests between individuals.

Social behaviours may involve aggression and conflict as individuals or groups fight to defend territories or to select a mate.

Social behaviour

In certain species the behaviour of some individuals in a social group is dominated by other individuals.Dominance means that one individual has greater

access to resources, such as food or mates, than other individuals in the group.

There may be a hierarchy of dominance – an individual’s position is often signalled by aggressive or submissive behaviours.

The most dominant individual is often a male, who eats first and has first choice of mates.

Culture

Cultural exchange is the passage of information from generation to generation by non-genetic means. Cultural learning involves activities such as:

selecting and preparing food;

catching prey;

recognising enemies;

defence;

learning songs;

migratory routes;

bonding behaviour;

courtship; and

reproductive behaviour.